Phylogenetic implications of the anatomical study of the Amburaneae clade (Fabaceae: Faboideae)

Abstract Phylogenetic analyses of early-diverging Faboideae have indicated that genera previously positioned in distinct tribes are instead closely related, e.g. in the Amburaneae clade, and the relatively recent rearrangements of many genera into clades has hampered the identification of morphological synapomorphies for previously unrecognized clades. Our aims are to evaluate anatomical vegetative characters of leaflets attached to reproductive features in the Amburaneae clade, to identify new synapomorphies for the clade and subclades, to identify characters supporting intergeneric relationships and diagnostic characters for the genus and species and to provide information about the morphology and histochemistry of secretory structures. The study was based on the anatomy of the leaflet of 19 species of the Amburaneae clade. Papillae cells, the presence of vascular system units and hypodermis are shared features of Amburaneae. Anatomical characters of the leaflet can be diagnostic at the generic and specific levels in Amburaneae. Secretory structures found in the clade are secretory cavities, secretory channels, idioblasts, mucilaginous epidermal cells and glandular trichomes. The broader concept of Amburaneae is reinforced here by morphological and molecular data, with the identification of new synapomorphies. Our dataset supports the intergeneric relationships resolved by molecular data.